Could someone please confirm that -- in the context of conducting a latent transition analysis (e.g., example 8.13) -- it is okay to add additional regression equations to the MODEL, so as to estimate the effect of a mediator M of X's effect on C1 and C2 classes?

I physically tested this in Mplus and received no error messages, but want to confirm it's okay since I see no solid instance of it being done.

Also, if you can point me to any references showing mediation in LTA using Mplus, I would be very grateful!